An example internal combustion engine is a dual fuel engine that includes a first type of fuel that may be utilized as the sole fuel during certain operating conditions and a second type of fuel that may be utilized in varying proportions in combination with the first type of fuel during other operating conditions. In certain applications, the first fuel source is a diesel fuel and the second fuel source is natural gas. The substitution of natural gas for diesel fuel can reduce the costs of operating the engine, particularly when the engine is employed at locations where natural gas is abundant or available at low cost. For example, in pressure pumping applications such as fracking rigs and equipment, dual-fuel engines may combust wellhead natural gas which is often unprocessed or minimally processed. Wellhead natural gas may have a wide range of quality characteristics derived from a varying combustible mixture of hydrocarbon gases including varying proportions of methane, ethane, propane, butane and/or pentane. Existing efforts to provide controls for dual fuel engines suffer from a number of drawbacks, limitations and shortcomings. There remains a significant need for the unique apparatuses, methods, systems and techniques disclosed herein.